I've linked to this thread from the other one.
On the 6400, my understanding is that the sub becomes "active" (maybe "more active" is the best way to put it) if you connect external speakers to the speaker jack on the rear of the system. They should be powered speakers, because the 6400 doesn't do any special powering of its speaker port. Many of them were used with Apple's monitors that had speakers built in, but it should work just as well with whatever powered computer speakers you have on hand. I happen to have used mine with the side-firing speakers on a Multiple Scan 15 (non-AV model, though it did still have speakers) and with the glorious audio system of an AudioVision 14-inch display.
Fun sidenote! With BeOS R5, you can manually control what audio outputs on the system are used, including enabling the subwoofer with no external speakers attached, and enabling the internal speaker when there's a headphone or speaker device attached to the system.
On the 6400, my understanding is that the sub becomes "active" (maybe "more active" is the best way to put it) if you connect external speakers to the speaker jack on the rear of the system. They should be powered speakers, because the 6400 doesn't do any special powering of its speaker port. Many of them were used with Apple's monitors that had speakers built in, but it should work just as well with whatever powered computer speakers you have on hand. I happen to have used mine with the side-firing speakers on a Multiple Scan 15 (non-AV model, though it did still have speakers) and with the glorious audio system of an AudioVision 14-inch display.
Fun sidenote! With BeOS R5, you can manually control what audio outputs on the system are used, including enabling the subwoofer with no external speakers attached, and enabling the internal speaker when there's a headphone or speaker device attached to the system.